A widely used method for making vinyl chloride monomer is the oxychlorination of ethylene to form ethylene dichloride which is subsequently dehydrohalogenated to form the vinyl chloride monomer. In the oxychlorination of ethylene, an oxygen source and hydrogen chloride are contacted with ethylene in the presence of a suitable catalyst.
Due to the relatively high price of ethylene versus ethane, processes for the preparation of vinyl chloride from ethane have been developed. One method comprises contacting ethane, an oxygen source and a chlorine source in the presence of a catalyst. The catalyst is typically a transition metal compound, such as cupric chloride or iron oxide, supported on a support structure or material, such as aluminum oxide. In addition to vinyl chloride monomer, ethylene is a reaction product. In refining this process, efforts have focused on maximizing the yield of vinyl chloride. British Patent Specification No. 1,039,369 discloses such a process in which water is used as an additional reagent, and that high yields of vinyl chloride can be obtained. The water is used to control the heat of the reaction, and since high levels of hydrogen chloride are added to maximize the yield of vinyl chloride, the water also preserves the iron oxide catalyst by preventing its conversion to iron chloride. The ethylene is separated from the vinyl chloride monomer and is recovered to be used in other processes. This process has two disadvantages. First, the separation of vinyl chloride from ethylene is a complex and costly step, and second, the yield of vinyl chloride per mole of ethane reagent is relatively low, typically less than 50%.
Therefore, it is desired to have a process for preparing ethylene from ethane wherein relatively small amounts of vinyl chloride are formed, and the conversion of ethane to ethylene is high. This ethylene prepared from ethane could then be fed directly to an oxychlorination reaction to be converted to ethylene dichloride, which could then be directly processed to vinyl chloride.